| Qianjiangsaurus | |
|---|---|
 | |
| Life restoration | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Hadrosauriformes |
| Superfamily: | †Hadrosauroidea |
| Genus: | †Qianjiangsaurus Dai et al.,2025 |
| Species: | †Q. changshengi |
| Binomial name | |
| †Qianjiangsaurus changshengi Dai et al., 2025 | |
Qianjiangsaurus (meaning "Qianjiang lizard") is anextinct genus ofhadrosauroidean ornithopod dinosaurs from theLate CretaceousZhengyang Formation of China. The genus contains asingle species,Q. changshengi, known from a partial skeleton.Qianjiangsaurus is one of the few hadrosauroids named from south China, and it indicates important fauna connections between similarly aged formations in Mongolia.
TheQianjiangsaurusholotype specimen, CLGRP V00016, was discovered by a paleontological expedition associated with the Chongqing Bureau of Geological and Mineral Resource Exploration and Development during the winter of 2022. The locality represents sediments of theZhengyang Formation near Zhengyang area inQianjiang District,Chongqing Municipality of southwest China. The specimen consists of a partial, somewhat articulated skeleton, comprising an incompletemandible, fourdorsal vertebrae, the sacrum, manycaudal vertebrae and associatedchevrons, most of thepelvic girdle, and several hindlimb bones.[1]
After being announced in August 2024 in a non-finalizedpreprint, Dai et al. (2025)describedQianjiangsaurus changshengi as a new genus and species of hadrosauroid dinosaurs based on these fossil remains. Thegeneric name,Qianjiangsaurus, combines "Qianjiang"—the name of the district containing thetype locality—with theGreekσαῦρος (sauros), meaning'lizard'. Thespecific name,changshengi, Changsheng Wang, the discoverer of the Chongqing fossil locality.[1]
Nanningosaurus, a genus from theNalong Basin ofGuangxi, is the only other hadrosauroid currently named from south China.[1][2]
The holotype ofQianjiangsaurus likely represents a mature adult individual. It is medium-sized in comparison to related taxa, at about 8 metres (26 ft) long.[1]
Theprepubic process of thepubis is fan-shaped, with a length:height ratio of about 0.79, representing the singleautapomorphy (uniquederived trait) identified in the holotype. The unique combination of other characters includes a total of 30dentary tooth positions with no more than five teeth peralveolus (tooth socket), acoronoid process at a right angle to the dentary, and seven fused vertebrae in the sacrum. While some of itsplesiomorphic (ancestral) anatomical features confidently place it within the Hadrosauroidea, it still demonstratesapomorphic (derived) features of later-diverging members of the Hadrosauridae, placing it as atransitional form between the two groups.[1]
In theirphylogenetic analyses, Dai et al. (2025) recoveredQianjiangsaurus as thesister taxon to the MongolianPlesiohadros,[3] with these taxa as late-diverging members of theHadrosauroidea outside of theHadrosauridae. Their results are displayed in thecladogram below:[1]
The discovery ofQianjiangsaurus provides further support for several faunal similarities between the Zhengyang Formation of China and theDjadokhta andBaruungoyot formations of Mongolia. These dinosaur parallels may indicate afaunal interchange between the two regions during the end of the Late Cretaceous, from the lateCampanian–earlyMaastrichtian. Whileabsolute dates have yet to be determined for the Zhengyang Formation, it was likely deposited during this time.[1]
Qianjiangsaurus is the first distinct dinosaur taxon to be named from the Zhengyang Formation. Fragmentary specimens belonging to unnamedtitanosaurs and theropods (includingtyrannosauroids and putativecarnosaurs) have also been found. Since large-scale excavations had not occurred in the region until 2022, additional specimens—such asornithomimosaurs,therizinosauroids,oviraptorosaurs as seen in coeval formations—may be found in the future.[1][4][5]
